Propeller for aircraft



A. BUERNER.

PROPELLER FUR MRCHAN.

APPLICATION FILED MAPLE. 192i- 'Patented Nov. 15, 192i.

"Talia Y Inventor. 19h/v0 .BeEn-N51? Attorney.

UNITED] STATES PATENT oFFlcE.

ARNO BOERNER, 0F SCHEVENI'NGEN, NETHERLANDS.

`PROFEI'JLEB, FOR AIRCRAFT.

Patented Nov. 15, 1.921.

Application led March 5, 1.921. Serial No. 450,113.

To all whom it may concern:

Be it known that I, ARNO BonRNEn, residing at Scheveningen, Netherlands, have invented certain new and useful Improvements in Propellers for Aircraft, of which the following isa specification.

This invention relates to propellers for aircraft of the kind in which the blades are adapted to slide radially to the propeller shaft and simultaneously to move angularly about an axis transverse to said shaft, whereby the resistance of the propeller can remain fixed at the amount required for an,

approximately uniform rotational speed of theengine under all conditions of atmospheric pressure.

The primary object of the invention is to provide a propeller of this kind and having automatic regulation in which the regulating members are exposed to minimum disturbance by centrifugal force.

Devices of the kind to which invention relates are particularly useful in engines of recent constructionl wherein the engine is fed with compressed air so that its output can be kept constant independently of the elevation.` v

In order that the invention may be understood there will now be described an embodiment thereofwith reference to the accompanying drawings and by way of example only. In these drawings Figure 1 illustrates a propeller with automatic regulation in longitudinal section, Fig. 2 a section on the line C-C of Fig. 1, and Fig.'

3 asection on the line D--D of Fig. 2.

In this propeller there is secured on the engine shaft 26 a twoart cylindrical casing 27 in which is radial y lmovable the inner end 28 of the blade`29, which end 428 is A powerful helical s ring 30 which abuts at one end against-the fiange 31 of the casing 27 and at the other end against a collar 32 of the hol- 'low cylinder 28 serving t`o guide the blade in the casing tends to hold the blade 29 in its innermost position'. In the cylindrical wall of the casing 27 are two diametrally opposed helical grooves 33, 34, entered by pro]ecting 35, 36 of the collar 32. `he propeller blade 37 is disposed with its cylindrical inner end in the hollow cylinder 28 on the inner wall of which it is guided by means of a flange' 38. .Between the flange 88 and the base ofthe casing. 27

is a strong helical spring 39 tending to hold the blade 37 in its innermost position. The hollow cylinder 28 has two diametrally opposedhelical grooves 40, 41 entered by projecting lugs 42,43 of the flange 38.

The helical grooves 33, 34 and 40, 41 are so designed that the pitch of the blades 29, 37 will be increased to the same extent when the blades are movedl equal distances outwardv in opposition to the action of the springs 30, 39. will be understood, the pitch of the grooves 40, 4l must be such as to yield twice as much ltwisting of the blade 37 as the grooves 33, 34: impart to the blade 29.

When the number of revolutions of the engine shaft 26 attains a certain amount, the blades 29, 37 commence to move outwardly automatically under the action of centrifugal force in opposition to the springs 30, 39, the outward movement increasing with the number of revolutions; at the same timethe pitch of the screw is increased.

The strength of the springs 30, 39 is such that the diameter of the propeller will have a predetermined value for each given number of revolutions; a proportionate increase of pitch of the propeller blades is attained by correct choice of the pitch of the helical grooves33, 34 and 40, 4.1` f

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In a propeller for aircraft, blades adapted under the iniuence of centrifugal force to slide radially to the shaft of the` propeller and simultaneously to move angul i ,to claim 1, a casing ada ted to inclose the telescoping, members an means securing sald shaft.

the springs, and

casing to the .propeller f In testimony whereofI aix my signature. i

ARNO BOERNER. 

